Winter active insects have different nature niche adaptations for getting warm compared to birds or mammals. Reptiles and amphibians are inactive in winter as are some mammals and many birds migrate to warmer regions. Most insects and other invertebrates are stuck here all winter. Many aquatic insects maintain activity in winter. Their activity along with that of other invertebrates is minimized.

Even when the ground is covered with snow, terrestrial insects can be seen actively going about their business of walking, jumping, or flying when conditions are suitable. Snowfleas are usually absent until well into the new year. They are not a flea but because they are small, black, and flip summersaults into the air, they have gained the name “flea.” A better name is springtail. When active on sunny winter days, they gather by the tens of thousands, usually at the base of large trees making the snow surface appear black.

Dark tree bark absorbs heat and radiates the sun’s warmth. Winter sun rays are not restricted from striking the trunk as they pass through the bare canopy branches. Springtails are soil inhabitants that come above ground where the snow has melted around the south side of the tree trunks. They have a small spine on the underside at their tail end that projects forward. It is locked in place at the spine’s tip.

Simulate the snapping mechanism that allows the springtail to flip summersaults into the air. Place two fingertips from opposite hands together at their very tip and provided increasing pressure until they snap apart. When the springtail lever snaps against the snow or hard surface it sends the lightweight an inch or two into the air to land somewhere nearby. A close view of massive snowfleas appears like jumping pepper on the snow.

Winter stoneflies, flies, and other insects fly on sunny winter days. When you see a name like stonefly with the two parts combined rather than separated to read stone fly, it indicates the species is not a true fly but belongs to a different classification Order. The same is true with snowflea.

To warm adequately to jump, walk, or fly, the organism must be small and usually dark. The dark body allows it to absorb sun energy and the small size allows heat energy to penetrate the body to warm muscles quickly. They also lose heat quickly. During short bursts of sun warmth, they can become active.

Large hibernating adult insects like the mourning cloak and eastern comma butterflies require a longer stretch of warming to bring their muscles to a temperature for flight. I have seen a mourning cloak come out of hibernation in early January but usually they are not active until near the spring equinox. Even so, I watch for them to become active in late February or early March before the sun crosses the equator and gets spring into high gear.

We might lay naked on the snow on a warm winter day but the sun will not warm us to a comfortable activity temperature by penetrating deep to our muscles like it does for a springtail. Instead, we will quickly suffer from hypothermia and die. I suggest we keep our oversized bodies bundled and lay in the snow making snow-angels. Each species has specialized body adaptations that allow it to function. Body size and color are important.

Habitat is critical. Aquatic insects, crayfish (can you tell by letter spacing if the crayfish is a true fish or not?), and fish can remain active in chilly liquid water. Their body temperature, though cool, allows activity all winter. Anglers know fish eat in winter but feeding and digestion are slowed in cold water compared to warm season rivers and lakes. Peer into an ice fishing hole from a dark ice fishing shanty where it is like watching TV with fish swimming through the viewing screen. Viewing is best when sunlight penetrates the ice.

Enjoy looking for active insects on beautiful sunny winter days when you rent snowshoes or get free use with your family membership at the Howard Christensen Nature Center. Take the family winter exploring in new ways during the coming months between the winter solstice on December 21 and spring equinox on March 20. There are always interesting things to do outdoors any time of year. Remain active and enjoy active insects.